This invention relates to dynamoelectric machines, and more specifically to electric motors and to a method of constructing electric motors. Even more specifically, this electric motor construction relates to a sealed electric motor which may be utilized in submerged or wet environments, such as submersible or sump pump applications.
Typically, a dynamoelectric or electric motor construction, particularly for fractional horsepower motors, comprises a stator assembly fitted into a cylindrical housing. Then, die cast or stamped metal end shields or bearing supports are applied to the ends of the housing and are secured thereto by through bolts extending from one of the end shields through the stator assembly to the other end shield. Alternatively, the end shields may be bonded to the ends of the housing with a suitale adhesive or may be welded thereto. Oftentimes, special tabs or mounting brackets are secured to the outer surfaces of the housing so as to permit the motor to be mounted with respect to its application.
While these prior art electric motor designs worked well for their intended purposes, the requirement of separately securing the end shields in place and providing mounting brackets was relatively time consuming and expensive during the manufacture of such motors. Also, in applications for submerged pumps and the like, the requirement of through bolts required that the through bolts be sealed.
Additionally, in motors utilized in pump applications or the like, it is often necessary to provide a seal around the rotor shaft of the motor so as to prevent leakage of water into the motor and to prevent lubricating oil and the like within the motor from leaking therefrom. Many such motors utilize part-spherical, self-aligning bearings such that the rotor shaft is journaled with respect to the end shields or bearing supports without binding in the journal bearings. These self-aligning bearings permit the axis of the rotor shaft to be disposed at a slight angle with respect to the diametric plane of the bearing supports or end shields such that the outer surfaces of the rotor shaft engageable with a seal carried by the end support may be somewhat skewed with respect to the sealing surfaces of the seal so as to possibly result in an imperfect seal or so as to result in undue wear on one side of the seal.